Temporary concrete abutments are used to mark and delineate vehicle traffic lanes. Concrete abutments of this type are commonly used in road construction areas to define temporary roadway or vehicle lanes. Because of space restrictions in construction areas, use of conventional roadside traffic control signs is not often practical. Accordingly, a problem arises as to the placement of traffic control signs such as signs advising motorists of legal speed limits, narrowing lanes, lane restrictions, curves, no stopping areas and the like. Accordingly, it has become a common practice to position traffic control signs on the top of concrete abutments which align the roadway. Traffic control signs are customarily clamped to the top of abutments using conventional clamping devices. However, conventional clamps such as C-clamps and the like do not provide adequate retention and gripping force, particularly when signs are located in close proximity to traffic lanes where passing vehicles, particularly, large trucks exert considerable vacuum or draft forces against the surface of the sign which may cause it to become loosened or to become dislodged from the abutment. Obviously, dislodgement of a traffic control sign poses an immediate and hazardous condition to both traffic and personnel in the area.